In a compelling demonstration Wandell (1995) showed that blurring the chromatic but not luminance layer of an image of a natural scene failed to elicit any impression of blur. Subsequent studies have suggested that the effect is due either to masking of the chromatic blur by the sharp luminance edges in the image (Sharman et al., 2013) or to a relatively compressed transducer function for chromatic blur (Kingdom et al., 2015). To test between these alternatives we first measured points of subjective equality (PSE) and precisions (thresholds) for Gaussian blurred circles. Perceived chromatic blur was found to be equal to perceived luminance blur, and was independent of contrast level. Introducing a sharp luminance step-edge had no effect on the perceived level of chromatic blur. However, in a subsequent experiment using images of natural scenes, the perceived blur of the chromatic layer was reduced in the presence of the luminance layer, as was also the chromatic blur precision (thresholds), in keeping with the results of Sharman et al. (2013). Yet, when the luminance layer was rotated relative to the chromatic layer, which removed the color-luminance edge correlations, chromatic blur precision was even worse, even although PSEs were restored to near-veridicality. We conclude that both luminance masking and chromatic scale compression contribute to the Wandell effect.